A simple method for measurement of cerebral blood flow using ¹²³I-IMP SPECT with calibrated standard input function by one point blood sampling; validation of calibration by one point venous blood sampling as a substitute for arterial blood sampling

In a simplified method for measurement of cerebral blood flow using one ¹²³I-IMP SPECT scan and one point arterial blood sampling (Autoradiography method), input function is obtained by calibrating a standard input function by one point arterial blood sampling. A purpose of this study is validation of calibration by one point venous blood sampling as a substitute for one point arterial blood sampling. After intravenous infusion of ¹²³I-IMP, frequent arterial and venous blood sampling were simultaneously performed on 12 patients of CNS disease without any heart and lung disease and 5 normal volunteers. The radioactivity ratio of venous whole blood which obtained from cutaneous cubital vein to arterial whole blood were 0.76 ± 0.08, 0.80 ± 0.05, 0.81 ± 0.06, 0.83 ± 0.11 at 10, 20, 30, 50 min after ¹²³I-IMP infusion, respectively. The venous blood radio activities were always 20% lower than those of arterial blood radioactivity during 50 min. However, the ratio which obtained from cutaneous dorsal hand vein to artery were 0.93 ± 0.02, 0.94 ± 0.05, 0.98 ± 0.04, 0.98 ± 0.03, at 10, 20, 30, 50 min after ¹²³I-IMP infusion, respectively. The venous blood radioactivity was consistent with artery. These indicate that arterio-venous difference of radioactivity in a peripheral cutaneous vein like a dorsal hand vein is minimal due to arterio-venous shunt in palm. Therefore, a substitution by blood sampling from cutaneous dorsal hand vein for artery will be possible. Optimized time for venous blood sampling evaluated by error analysis was 20 min after ¹²³I-IMP infusion, which is 10 min later than that of arterial blood sampling.